I think terrorist factions are far too small to start a full scale war, or even a World War 3. Yet, their size and therefor their following warfare type, is still a problem. Terrorism is a warfare type. They do terrorize because they can not annihilate in great numbers. It is also a psychological warfare, by seeding intense fear amongst their enemies.
And talking about their motivations. I think Barrack Obama knows exactly what they are, and I don't want to waist too much words about them either (they ain't got a live

). But the U.S. President was considering if not already gave, lots and lots of money to the military. But apparently his advisers told him that this conflict could escalate.
I don't know how exactly such a escalation is supposed to look, but I would say: If the loss on US side is minimal, just wipe those idiots out! ... but I think the military has actually problems to find them, in the first place.